Re: [Qemu-devel] [PATCH 4/5] Disable XBZRLE during migrate to file if it is active

[Orit Wasserman]

On 01/30/2013 07:59 PM, Eric Blake wrote:
> On 01/30/2013 03:35 AM, Orit Wasserman wrote:
>> XBZRLE is not effective when migrating to file.
> 
> Why not?  When doing a live migration to file, the same sector of memory
> can be visited more than once in the migration stream, and thus
> compressing the later pages should make the saved file smaller.  I'm not
> sure I buy this argument of XBZRLE being incompatible with migration to
> file, at least without not more explanation why it fails.
> 
Users usually use compression when migrating to file (like gzip), double 
compression
is usually much less effective.
Migration fails because the XBZRLE capability is not set,
this is happens when we load the file in the command line ( -incoming 
"exec:gzip -c -d vm.gz").
Paolo suggest a better workaround which doesn't require disabling XBZRLE,
see v2 of the series.

Orit